PUT /teamMember

Add a member to the Team. Note: The request is authenticated by a hash
message authentication code in the request body, generated by Synapse. The intended use of this
service is by the portal, completing a round trip with a 'one-click join-team'
link provided to the user by Synapse via email. If both teamEndpoint and
notificationUnsubscribeEndpoint are provided, notification email(s) will
be sent to the appropriate parties.